An insulated gate bipolar transistor (Insulated Gate Bipolar Transistor, abbreviated as IGBT) has the advantages of an MOSFET device such as a high input impedance and the advantages of a giant transistor (i.e., Giant Transistor, abbreviated as GTR) such as a high-speed switching characteristic, and is widely applied to an alternating current motor, a frequency converter, a switching power supply, a lighting circuit and traction drive or other fields.
In fabricating the IGBT device, multiple separate IGBT cellular zones (each of the IGBT cellular zones includes multiple IGBT cells) are generally formed on a wafer firstly, and are cut into multiple single-grained IGBT chips. Each of the IGBT chips includes a separate cellular emitter, a separate cellular collector and a separate cellular gate. Then, qualified IGBT chips are interconnected and packaged, to form an IGBT device. However, the IGBT device fabricated by the method described above has a low utilization rate of package size since the IGBT device is formed through interconnection and packaging of multiple IGBT chips, thereby leading to a low utilization rate of current-carrying area in the device and a weak current-carrying capacity; the IGBT chips may come from different wafers, which results in that the IGBT chips have different thickness and electrical parameters, the IGBT chips are under different pressure when being packaged, and it is difficult to control the electrical parameters of the IGBT device after packaging.
In diagram of this, an IGBT device formed through packaging a whole-wafer IGBT chip emerges. In the whole-wafer IGBT chip, multiple interconnected IGBT cellular zones are formed on a wafer, and the whole-wafer IGBT chip can be packaged directly without cutting, to form the IGBT device. The IGBT cellular zones have high integration and a strong current-carrying capacity. In addition, the whole wafer is packaged, thus package pressure is uniform, and it is easy to control the electrical parameters.
A failure cellular zone exists in the cellular zones of the whole-wafer IGBT chip, and the failure cellular zone may have a harmful effect on the performance of the IGBT device. To avoid the harmful effect of the failure cellular zone on the performance of the IGBT device is an urgent issue in fabricating the IGBT device.